<html lang="zh-cn">
  <head>
    <title>center flex</title>
    <style>
      body {
        margin: 0;
        padding: 0;
        display: flex;
        justify-content: center;
        align-items: center;
      }
      .list {
        width: 24%;
        height: 200px;
        background-color: skyblue;
      }
    </style>
  </head>
  <body>
    <div class="list"></div>
  </body>
</html>
